/*
 * Copyright (c) 2006, Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * This file is part of the uIP TCP/IP stack
 *
 * $Id: uip-neighbor.c,v 1.2 2006/06/12 08:00:30 adam Exp $
 */

/**
 * \file
 *         Database of link-local neighbors, used by IPv6 code and
 *         to be used by a future ARP code rewrite.
 * \author
 *         Adam Dunkels <adam@sics.se>
 */

#include "uip-neighbor.h"

#include <string.h>

#define MAX_TIME 128

#ifdef UIP_NEIGHBOR_CONF_ENTRIES
#define ENTRIES UIP_NEIGHBOR_CONF_ENTRIES
#else /* UIP_NEIGHBOR_CONF_ENTRIES */
#define ENTRIES 8
#endif /* UIP_NEIGHBOR_CONF_ENTRIES */

struct neighbor_entry {
    uip_ipaddr_t ipaddr;
    struct uip_neighbor_addr addr;
    u8_t time;
};
static struct neighbor_entry entries[ENTRIES];

/*---------------------------------------------------------------------------*/
void
uip_neighbor_init(void)
{
    int i;

    for (i = 0; i < ENTRIES; ++i) {
        entries[i].time = MAX_TIME;
    }
}
/*---------------------------------------------------------------------------*/
void
uip_neighbor_periodic(void)
{
    int i;

    for (i = 0; i < ENTRIES; ++i) {
        if (entries[i].time < MAX_TIME) {
            entries[i].time++;
        }
    }
}
/*---------------------------------------------------------------------------*/
void
uip_neighbor_add(uip_ipaddr_t ipaddr, struct uip_neighbor_addr *addr)
{
    int i, oldest;
    u8_t oldest_time;

    /* Find the first unused entry or the oldest used entry. */
    oldest_time = 0;
    oldest = 0;
    for (i = 0; i < ENTRIES; ++i) {
        if (entries[i].time == MAX_TIME) {
            oldest = i;
            break;
        }
        if (uip_ipaddr_cmp(entries[i].ipaddr, addr)) {
            oldest = i;
            break;
        }
        if (entries[i].time > oldest_time) {
            oldest = i;
            oldest_time = entries[i].time;
        }
    }

    /* Use the oldest or first free entry (either pointed to by the
       "oldest" variable). */
    entries[oldest].time = 0;
    uip_ipaddr_copy(entries[oldest].ipaddr, ipaddr);
    memcpy(&entries[oldest].addr, addr, sizeof(struct uip_neighbor_addr));
}
/*---------------------------------------------------------------------------*/
static struct neighbor_entry *
find_entry(uip_ipaddr_t ipaddr)
{
    int i;

    for (i = 0; i < ENTRIES; ++i) {
        if (uip_ipaddr_cmp(entries[i].ipaddr, ipaddr)) {
            return &entries[i];
        }
    }
    return NULL;
}
/*---------------------------------------------------------------------------*/
void
uip_neighbor_update(uip_ipaddr_t ipaddr)
{
    struct neighbor_entry *e;

    e = find_entry(ipaddr);
    if (e != NULL) {
        e->time = 0;
    }
}
/*---------------------------------------------------------------------------*/
struct uip_neighbor_addr *
uip_neighbor_lookup(uip_ipaddr_t ipaddr)
{
    struct neighbor_entry *e;

    e = find_entry(ipaddr);
    if (e != NULL) {
        return &e->addr;
    }
    return NULL;
}
/*---------------------------------------------------------------------------*/
